The subject matter described herein relates generally to systems for filling a gas cylinder.
Current cylinder filling products require the operator of the equipment to manually adjust a restrictor valve to control the rate at which air is transferred into a cylinder for storing a gas, such as a self-contained breathing apparatus (SCBA) or self-contained underwater breathing apparatus (SCUBA) cylinder. If the cylinder(s) are filled too rapidly, the air heats up to such a degree that expansion of the air creates a condition causing the cylinder to be less than completely filled when the air subsequently cools down. Additionally, when the cylinder is filled too slowly this creates an inefficient use of the operator's time. The filling process may be dependent on the skill level of the operator experience as the valve may require continuous adjustment to achieve an optimal filling rate.
In order to help achieve the optimum fill rate known cylinder filling products may include an automatic flow control valve. For example, FIG. 1 illustrates a currently known automatic flow control valve 45. The automatic flow control valve 45 may incorporate a needle valve 50 controlled through a spring 52 and a piston 54 that is acted upon by storage pressure. As such, when the storage pressure is high, the needle valve 50 closes to restrict the gas flow rate through the automatic flow control valve 45. However, the gas flow rate may be controlled in proportion to storage pressure. This may be disadvantageous in that the needle valve may remain at its most restricted position if the storage pressure remains high, even as the pressure in the cylinder being filled increases resulting. The restricted positioning of the needle valve may result in a steadily decreasing gas flow rate. Other known systems utilize a manual control to control the gas flow rate. FIG. 2 illustrates a schematic of a known gas cylinder filing system with manual control. As shown in FIGS. 2A and 2B, the cylinder filling system utilizes a manually operated control valve 56 to control the amount of pressure delivered to one or more cylinders 58 from a compressor 60.